Impact-absorbing material

Abstract

The present invention relates to an impact-absorbing material including a foam having a thickness of from 0.1 to 1.0 mm, an average cell size of from 10 to 65 μm and a density of from 0.01 to 0.20 g/cm 3 and having an impact-absorbing property, as defined in the following expression (1), of from 40 to 90%: Impact-absorbing property (%)=(F 0− F 1 )/F 0 ×100 (1), in which F 0 represents an impact force at the time of making an impactor collide with only a support plate; and F 1 represents an impact force at the time of making an impactor collide with a support plate of a structure composed of the support plate and the impact-absorbing material.

1 . An impact-absorbing material comprising a foam having a thickness of from 0.1 to 1.0 mm, an average cell size of from 10 to 65 μm and a density of from 0.01 to 0.20 g/cm 3  and having an impact-absorbing property, as defined in the following expression (1), of from 40 to 90%:
   Impact-absorbing property(%)=( F 0− F 1)/ F 0×100  (1)
 
 
       wherein F 0  represents an impact force at the time of making an impactor collide with only a support plate; and F 1  represents an impact force at the time of making an impactor collide with a support plate of a structure composed of the support plate and the impact-absorbing material. 
     
     
         2 . The impact-absorbing material according to  claim 1 , having an impact-absorbing characteristic such that, in a falling ball test in which a laminate obtained by laminating a polarizing plate, an LCD panel, a double-coated pressure-sensitive adhesive tape, the impact-absorbing material and a double-coated pressure-sensitive adhesive tape in this order, with the polarizing plate being an upper surface, is used as a module, and after locating an acrylic plate on the upper surface of the module, an operation of freely falling a 0.39 N-steel ball on the acrylic plate from a height of 150 cm is repeated until the LCD panel is broken, the number of repetition measured at the time when the breakage is first generated on the LCD panel is 80 times or more. 
     
     
         3 . The impact-absorbing material according to  claim 1 , having a load against repulsion upon compression to 0.1 mm-thickness of from 0.005 to 0.100 MPa. 
     
     
         4 . The impact-absorbing material according to  claim 1 , having a tensile strength of from 3.0 to 11.0 MPa. 
     
     
         5 . The impact-absorbing material according to  claim 1 , wherein the foam is formed through steps of impregnating a resin composition with a high-pressure inert gas and then reducing the pressure. 
     
     
         6 . The impact-absorbing material according to  claim 1 , wherein the foam is formed through steps of impregnating an unfoamed molded article comprising a resin composition with a high-pressure inert gas and then reducing the pressure. 
     
     
         7 . The impact-absorbing material according to  claim 1 , wherein the foam is formed through steps of impregnating a molten resin composition with an inert gas under pressure and then reducing the pressure and simultaneously molding. 
     
     
         8 . The impact-absorbing material according to  claim 5 , wherein heating is carried out after the pressure reduction or simultaneously with the pressure reduction. 
     
     
         9 . The impact-absorbing material according to  claim 6 , wherein heating is carried out after the pressure reduction or simultaneously with the pressure reduction. 
     
     
         10 . The impact-absorbing material according to  claim 7 , wherein heating is carried out after the pressure reduction or simultaneously with the pressure reduction. 
     
     
         11 . The impact-absorbing material according to  claims 5 , wherein the inert gas is carbon dioxide. 
     
     
         12 . The impact-absorbing material according to  claims 6 , wherein the inert gas is carbon dioxide. 
     
     
         13 . The impact-absorbing material according to  claims 7 , wherein the inert gas is carbon dioxide. 
     
     
         14 . The impact-absorbing material according to  claim 5 , wherein the inert gas is in a supercritical state. 
     
     
         15 . The impact-absorbing material according to  claim 6 , wherein the inert gas is in a supercritical state. 
     
     
         16 . The impact-absorbing material according to  claim 7 , wherein the inert gas is in a supercritical state. 
     
     
         17 . The impact-absorbing material according to  claim 1 , wherein a pressure-sensitive adhesive layer is provided on one surface or both surfaces of the foam. 
     
     
         18 . The impact-absorbing material according to  claim 17 , wherein the pressure-sensitive adhesive layer is formed on the foam through a film layer. 
     
     
         19 . The impact-absorbing material according to  claim 17 , wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive.